RETRACTED: Synthesis of hollow structured Bi4O5Br2/Cu2O P–N heterojunctions with large surface area for enhanced photocatalytic performance towards the degradation of organic dyes

Cu2O nanoparticles have been anchored on the surface of Bi4O5Br2 hollow nanocubes, and the resulting composites have been tested for the photocatalytic degradation of organic dyes under visible light. The as-synthesized composites are composed of Bi4O5Br2 in the monoclinic phase and Cu2O in the cubic phase, both of which respond to visible light. The optimized Bi4O5Br2/Cu2O composite can decompose 95% of initial RhB and 99% of initial MB after 80 min illumination, which is significantly higher than those obtained on bare Bi4O5Br2 and Cu2O photocatalysts. The charge transfer and separation dynamics in the Bi4O5Br2/Cu2O composite photocatalysts under excitation are proved to be superior compared to bare Bi4O5Br2 in the electrochemical measurements. The enhanced performance of the Bi4O5Br2/Cu2O composite is attributed to the p-n junction formed between Bi4O5Br2 and Cu2O, which inhibits charge recombination and facilitates effective charge separation. Lastly, it has been proved in the scavenger tests that superoxide radical is the most crucial active species in the photocatalytic degradation of RhB.